From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-22.4 required=3.0 tests=BAYES_00,DKIMWL_WL_MED, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,MENTIONS_GIT_HOSTING,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_IN_DEF_DKIM_WL autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id B1628C4727D for ; Fri, 25 Sep 2020 12:03:31 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 6DDDE21D7A for ; Fri, 25 Sep 2020 12:03:31 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="MDPyV9Jy" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728171AbgIYMD2 (ORCPT ); Fri, 25 Sep 2020 08:03:28 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:59446 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728147AbgIYMD1 (ORCPT ); Fri, 25 Sep 2020 08:03:27 -0400 Received: from mail-wm1-x341.google.com (mail-wm1-x341.google.com [IPv6:2a00:1450:4864:20::341]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 9BC76C0613D3 for ; Fri, 25 Sep 2020 05:03:27 -0700 (PDT) Received: by mail-wm1-x341.google.com with SMTP id d4so2764279wmd.5 for ; Fri, 25 Sep 2020 05:03:27 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20161025; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=j5bxVuVEiqgVlanRePu6dA6f3zbOwxopbpYSWu4POWk=; b=MDPyV9JyNqYevanfnR1rtU6bGSJi5p22RFCAgfzYRhndYJbn0RxvNFymUBVUq4yloI S4qD6N6aOmqKaKJ3GB85EN9rAv8IUaxoqgdb2mNeMJVMshswtqP8T9ylfJpuZA9UkUn3 l7EQm23e1bLg8EJyQYf2M+9sF2W4Lbs7Dfb9HQFMp9OH9hrCRW4UQL1+TesXYm1WCV9n 1R7zAWPZCAoRcuosg+vaNhWV4JbAa5ufV/0bCW488jixR38gD9VA8YMaIwYyW4NOEKuE BifDoz1UDzLiL4YUjGcDGeBtDvXAvEHLGETy/hu8aZmzt5HxukVVB+giAbqqqNk+DLw9 ov2A== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=j5bxVuVEiqgVlanRePu6dA6f3zbOwxopbpYSWu4POWk=; b=eSzW4g09MWeARuM7879a9mUTgGQmXfY7h10bV+Iyaj+xxRQiSPDrq7IBwZLYSvmqtc TmOp72NyBJ+/w2avMJhJi8OnqmWYLiK1Nv/mWrNh1QeFDUQ8XUFV7yfuTRmE3CkW5nOQ RoX7jpbq9q8NW16gOe3TW9O1F6BFPi4u6gltfXY85EWKy5khQ2NChr3Mkll0zkOIIbGx ks1rEUvtx8cGpF/K1cVTvj2iRGjlqFOb+np6yXaLVyVbYU7vQm5Fyb5LFq1eP49ajkza KQPDuMBQTrToz7xMG/oXhEutxTD4mI1N7W5ekrJkhdO5q3GpVHTHH0jaruW6n2zq977u N1yw== X-Gm-Message-State: AOAM532+vtUGSF0fgRkK7tiSwi2GM9n7/RGfWTtx8+Yj64xWW7xSPaJ7 uQrnvZr6go6B7eupnu7sADaj5nzjQKkCSw/sPJdB5Q== X-Google-Smtp-Source: ABdhPJwVtZag41aA0S3BJWbfmQKAI4dJew+ojCY35ogBbonXZ4WZsj9CG4j40D5B/FOP70hS4l9dJdXHX+9Fd2IJojg= X-Received: by 2002:a7b:cd05:: with SMTP id f5mr2753455wmj.116.1601035405961; Fri, 25 Sep 2020 05:03:25 -0700 (PDT) MIME-Version: 1.0 References: <20200921155004.v2.1.I67a8b8cd4def8166970ca37109db46d731b62bb6@changeid> In-Reply-To: From: Archie Pusaka Date: Fri, 25 Sep 2020 20:03:14 +0800 Message-ID: Subject: Re: [PATCH v2] Bluetooth: Check for encryption key size on connect To: Luiz Augusto von Dentz Cc: linux-bluetooth , Marcel Holtmann , CrosBT Upstreaming , Archie Pusaka , Alain Michaud , "David S. Miller" , Jakub Kicinski , Johan Hedberg , Linux Kernel Mailing List , "open list:NETWORKING [GENERAL]" Content-Type: text/plain; charset="UTF-8" Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org Hi Luiz, On Wed, 23 Sep 2020 at 01:03, Luiz Augusto von Dentz wrote: > > Hi Archie, > > On Tue, Sep 22, 2020 at 12:48 AM Archie Pusaka wrote: > > > > Hi Luiz, > > > > On Tue, 22 Sep 2020 at 01:15, Luiz Augusto von Dentz > > wrote: > > > > > > Hi Archie, > > > > > > > > > On Mon, Sep 21, 2020 at 12:56 AM Archie Pusaka wrote: > > > > > > > > From: Archie Pusaka > > > > > > > > When receiving connection, we only check whether the link has been > > > > encrypted, but not the encryption key size of the link. > > > > > > > > This patch adds check for encryption key size, and reject L2CAP > > > > connection which size is below the specified threshold (default 7) > > > > with security block. > > > > > > > > Here is some btmon trace. > > > > @ MGMT Event: New Link Key (0x0009) plen 26 {0x0001} [hci0] 5.847722 > > > > Store hint: No (0x00) > > > > BR/EDR Address: 38:00:25:F7:F1:B0 (OUI 38-00-25) > > > > Key type: Unauthenticated Combination key from P-192 (0x04) > > > > Link key: 7bf2f68c81305d63a6b0ee2c5a7a34bc > > > > PIN length: 0 > > > > > HCI Event: Encryption Change (0x08) plen 4 #29 [hci0] 5.871537 > > > > Status: Success (0x00) > > > > Handle: 256 > > > > Encryption: Enabled with E0 (0x01) > > > > < HCI Command: Read Encryp... (0x05|0x0008) plen 2 #30 [hci0] 5.871609 > > > > Handle: 256 > > > > > HCI Event: Command Complete (0x0e) plen 7 #31 [hci0] 5.872524 > > > > Read Encryption Key Size (0x05|0x0008) ncmd 1 > > > > Status: Success (0x00) > > > > Handle: 256 > > > > Key size: 3 > > > > > > > > ////// WITHOUT PATCH ////// > > > > > ACL Data RX: Handle 256 flags 0x02 dlen 12 #42 [hci0] 5.895023 > > > > L2CAP: Connection Request (0x02) ident 3 len 4 > > > > PSM: 4097 (0x1001) > > > > Source CID: 64 > > > > < ACL Data TX: Handle 256 flags 0x00 dlen 16 #43 [hci0] 5.895213 > > > > L2CAP: Connection Response (0x03) ident 3 len 8 > > > > Destination CID: 64 > > > > Source CID: 64 > > > > Result: Connection successful (0x0000) > > > > Status: No further information available (0x0000) > > > > > > > > ////// WITH PATCH ////// > > > > > ACL Data RX: Handle 256 flags 0x02 dlen 12 #42 [hci0] 4.887024 > > > > L2CAP: Connection Request (0x02) ident 3 len 4 > > > > PSM: 4097 (0x1001) > > > > Source CID: 64 > > > > < ACL Data TX: Handle 256 flags 0x00 dlen 16 #43 [hci0] 4.887127 > > > > L2CAP: Connection Response (0x03) ident 3 len 8 > > > > Destination CID: 0 > > > > Source CID: 64 > > > > Result: Connection refused - security block (0x0003) > > > > Status: No further information available (0x0000) > > > > > > > > Signed-off-by: Archie Pusaka > > > > Reviewed-by: Alain Michaud > > > > > > > > --- > > > > Btw, it looks like the patch sent by Alex Lu with the title > > > > [PATCH] Bluetooth: Fix the vulnerable issue on enc key size > > > > also solves the exact same issue. > > > > > > > > Changes in v2: > > > > * Add btmon trace to the commit message > > > > > > > > net/bluetooth/l2cap_core.c | 3 ++- > > > > 1 file changed, 2 insertions(+), 1 deletion(-) > > > > > > > > diff --git a/net/bluetooth/l2cap_core.c b/net/bluetooth/l2cap_core.c > > > > index ade83e224567..b4fc0ad38aaa 100644 > > > > --- a/net/bluetooth/l2cap_core.c > > > > +++ b/net/bluetooth/l2cap_core.c > > > > @@ -4101,7 +4101,8 @@ static struct l2cap_chan *l2cap_connect(struct l2cap_conn *conn, > > > > > > > > /* Check if the ACL is secure enough (if not SDP) */ > > > > if (psm != cpu_to_le16(L2CAP_PSM_SDP) && > > > > - !hci_conn_check_link_mode(conn->hcon)) { > > > > + (!hci_conn_check_link_mode(conn->hcon) || > > > > + !l2cap_check_enc_key_size(conn->hcon))) { > > > > > > I wonder if we couldn't incorporate the check of key size into > > > hci_conn_check_link_mode, like I said in the first patch checking the > > > enc key size should not be specific to L2CAP. > > > > Yes, I could move the check into hci_conn_check_link_mode. > > At first look, this function is also called by AMP which I am not > > familiar with. In addition, I found this patch which moves this check > > outside hci_conn, so I have my doubts there. > > https://git.kernel.org/pub/scm/linux/kernel/git/bluetooth/bluetooth-next.git/commit/?id=693cd8ce3f882524a5d06f7800dd8492411877b3 > > Right, I think we can have it as part of the hci_conn_check_link_mode, > that said it is perhaps better to have it as > hci_conn_check_enc_key_size instead as it is not L2CAP expecific. > Other than that it looks good to me. Do you mean we should move l2cap_conn_check_enc_key_size to hci_conn_check_enc_key_size? I think that is a good idea. We also have hci_conn_check_secure which I am unsure what the purpose is. I'll try to merge them together. > > > > > > > > conn->disc_reason = HCI_ERROR_AUTH_FAILURE; > > > > result = L2CAP_CR_SEC_BLOCK; > > > > goto response; > > > > -- > > > > 2.28.0.681.g6f77f65b4e-goog > > > > > > > > > > > > > -- > > > Luiz Augusto von Dentz > > > > Thanks, > > Archie > > > > -- > Luiz Augusto von Dentz Thanks, Archie